I thought that when the beys fuse that Phi And Heartz would fuse. I was wrong Pheonix just absorbs Dead Hades' dark power. Take a look at this 

I'm glad it ended that way I think it would've been ridiculous if phi and hearts fuse, beyblade burst may have some Ilogical things some times but still try to keep it real and not to supernatural, this would straight up like a metal saga thing if they had fuse. And that alien and immortal thing too was clear off in this episode I never believe that phi got out of a meteor are he was an alien , it was just a panel showing phi walking after the meteor crash its just for effect and hype the character. So I'm glad all of those things a clear of in this episode, IMO I think burst work better with limited supernatural mixed in the story.

Yeah,now that I think about it I agree